The impact of polarization-dependent loss on the constant modulus algorithm for varying number of fiber spans based on an outage criterion

We investigate the effect of polarization-dependent loss (PDL) on the constant modulus algorithm (CMA) in 4-QAM and 16-QAM polarization multiplexed (PolMux) systems with varying number of fiber spans and different PDL values. To quantify this effect, outage probability is introduced as the probability of having a signal-to-noise ratio (SNR) degradation smaller than 1 dB 99% of the time. We observe that by increasing the number of fiber spans, the SNR penalty for CMA reaches a limiting value. Moreover, in the 16-QAM multi-span case, the effect of PDL on CMA depends on the amount of PDL, while for 4-QAM, the effect of PDL on CMA is insensitive to the amount of PDL. These results will provide guidelines for designing systems and adjusting transmission power.